Hello!! Some Newbie advice needed :D

[JohnD]

35 minutes ago, SLeonard said:

 

cyl  reading1   reading 2

1      161         160                                            
2     175         175
3     171         170    Wet Spark plug
4     166         165

Mean pressure 168

So 1/ -4.7

      2/ +4

      3/ +2

      4/ -3   

All good!  But No.3 does look grumous!   Are you sure it's firing OK?  Check the lead and dizzie cap.

JOhn

 

[Josef]

On 29/08/2023 at 08:36, SLeonard said:

Hi @johny . Not sure if I have an earlier mkiv dash, or it changed, but I have 1 orange light towards the passenger side of the car/ dash and 1 red light to the direct left of the main dials in the dash (never ever comes on even on ignition). No lights in the speedo. 

You have the wrong speedo then. Not that it makes any difference so long as everything works as expected, but all Spitfires had the oil pressure, main beam and ignition warning lights at the bottom of the speedo. 

[SLeonard]

43 minutes ago, Josef said:

You have the wrong speedo then. Not that it makes any difference so long as everything works as expected, but all Spitfires had the oil pressure, main beam and ignition warning lights at the bottom of the speedo. 

@Josef I’ve realised it has Smiths aftermarket dials, so I expect a previous owner has fitted lights to the dash. Orange is the ignition warning/ charging light. Blue is main beam. Red I would imagine is the oil pressure. Not sure if that should also light on ignition on as a test, but never does. 

[SLeonard]

2 hours ago, JohnD said:

cyl  reading1   reading 2

1      161         160                                            
2     175         175
3     171         170    Wet Spark plug
4     166         165

Mean pressure 168

So 1/ -4.7

      2/ +4

      3/ +2

      4/ -3   

All good!  But No.3 does look grumous!   Are you sure it's firing OK?  Check the lead and dizzie cap.

JOhn

 

@JohnDIt was but not anymore 😂. Spark plug gaps were too large so I’ve reduced them to 0.025, and its been rough ever since, with uneven idle and drove terribly. Spark plug 3 is really wet with oil so its getting in somewhere. I’m going to recheck leads and plugs tomorrow but I also suspect oil is passing the valves on cylinder 3

[johny]

I suppose it would have to be the inlet valve as this is the one where oil could be 'sucked' in but why just cylinder 3? All the valve guides should wear pretty much equally....

[Pete Lewis]

doesnt matter what colour the oil/charge warnings are but both must illuminate when you switch on  if not then a bulb is blown or wiring /contact problems exist 

it is most important the charge light is fully operational or charging will suffer 

and a question about running and wet plug   what spark plugs are used    you donr want an R in the suffix 

Pete

[Josef]

On 30/08/2023 at 22:25, SLeonard said:

oil pressure. Not sure if that should also light on ignition on as a test, but never does. 

You’re right, the oil pressure light should come on at first start. The switch on the RHS of the block is a pressure sensor, and for the first few seconds of running you won’t have built up enough oil pressure to trigger it and extinguish the dash light. Check the bulb first, then the wiring, and if they’re both OK it’s new switch time. 

[Pete Lewis]

what spark plugs are fitted???????

if you have unglazed plugs then the prior rich running will contaminate the insulation and break down under load 

here are some waffle about all this and use plugs with an R in the suffix they cork up our low HT 

 

[SLeonard]

Plugs and gaps are good. Cleaned and rebalanced the carbs and fixed the throttle linkage sticking. Car is running smooth with good power through the range and idling smooth at ~600 rpm. Might raise the idle slightly as get the charge light especially when fan is on, but its happy and voltage is 14V.
 

Still pulls oil but nowhere as bad at the moment. We’re going to overhaul the valves and head in the next few weeks and fix various engine leaks. 
 

Thanks to everyone for their help! We have a happy 18yr old who now knows how to balance carbs, and a chuffed 45yr old whose dusted off some nearly forgotten skills. Here’s to some happy motoring!!

[Pete Lewis]

i will ask again    what plugs are fitted     need the make a suffix numbers        "good"   doesnt make an answer  for us to help

Pete

[SLeonard]

12 minutes ago, Pete Lewis said:

i will ask again    what plugs are fitted     need the make a suffix numbers        "good"   doesnt make an answer  for us to help

Pete

Thanks @Pete Lewis  We will pull the plugs soon as we are replacing. Any suggestions which ones and we’ll happily go with those. The existing plugs need binning anyway as they are pretty choked and obviously one is pretty wet. We’re fixing the oil issue and switching the plugs at the same time. Meantime, the car starts on the button and is smooth so I’m happy the issues are resolved. 

Edited September 1, 2023 by SLeonard

[johny]

3 minutes ago, SLeonard said:

 We’re fixing the oil issue and switching the plugs at the same time.

Where was the oil found to be coming from in the end?

[Pete Lewis]

most std plugs used would be a NGK BP5/6ES   do not use any with an R in the suffix   our HT is corked up if you get sold some as ok  they will weaken the spark

there are some you tube on testing how bad this is .

NGK are not glazed now (as many are not) as injection doesnt give the rich sooty problems of carb fueling on choke so the process was discontinued 

if the engine is run frequenlty hot and cleared out they will last for years , if its sick they wont last long 

Pete

[SLeonard]

On 02/09/2023 at 13:33, Pete Lewis said:

most std plugs used would be a NGK BP5/6ES   do not use any with an R in the suffix   our HT is corked up if you get sold some as ok  they will weaken the spark

there are some you tube on testing how bad this is .

NGK are not glazed now (as many are not) as injection doesnt give the rich sooty problems of carb fueling on choke so the process was discontinued 

if the engine is run frequenlty hot and cleared out they will last for years , if its sick they wont last long 

Pete

They are NGK BP6ES. 
 

So, pretty sure the fuel mix is right (colortune blue flame and idle stable when lifting the carb piston 1mm. 

The car runs under light load and at even speed, but as soon as you go open throttle it hesitates and stutters and doesn’t go. Sometimes this clears and it behaves for a few streets, then it comes back again. 2 days of tuning carbs I’m sure its good, and spark plugs are cleaning up and starting to tan now its been run a bit. 
 

previous owner ran E10 and lad has just put 97ron in. Not sure why this would matter, unless its messed up the timing. 

[Steve P]

These engines were designed when 100ron fuel was the norm.

My 2 cars run terribly on 95 octane E10.I use nothing but Shell V Power if i can get it.

Steve

[Pete Lewis]

we have spent most of the morning with a local 1500 sick as a pig

the main culprit amongst a number of now whats   was the fuel pipe to the jet was seriously kinked under the spiral wrap 

and  luckily no waxstats  to fix  and a leaking rocker gasket upsetting the idle due to air ingress which raised an uncontrollable high idle 

Pete

[Peter Truman]

1 hour ago, Pete Lewis said:

 

 the fuel pipe to the jet was seriously kinked under the spiral wrap 

Pete

Interestingly the most recent SU rebuild kit I fitted the float chamber to jet pipe was too long and hampered the linkage operation on forcing it to clear the linkage I kinked the pipe, solution was to shorten the pipe a little by repeated short lengths to get it right. Once kinked it obviously easily kinks again so beware!! 

[Pete Lewis]

its been reported a number of times that you need to cut 3mm approx off the tube to get a smooth choke operation and no kink 

seems its pretty common SU aftermarket spares problem 

its something all you SU users need to be aware of 

Pete